The research objective is synthesis of a conjugate of mitomycin C to an antisense phosphorothioate nucleotide targeted to proliferating smooth muscle cells responsible for arterial occlusion. This would provide a novel approach to the prevention of restenosis, for which there is currently no effective medicinal intervention available. Mitomycins will be derivatized with a linking group to permit covalent attachment to the 5' end of end of an antisense oligonucleotide, either while attached to the solid support, or after cleavage of the oligonucleotide from the solid support. Compounds will be assayed in a cell culture assay to evaluate the effectiveness of such agents compared to either of the components individually or co-administered,to determine if synergistic activity against cell proliferation is achieved. In principle, we envisage the antisense oligonucleotide hybridizing with RNA in a smooth muscle cell and permitting the attached mitomycin C to covalently modify an adjacent guanine base, thereby preventing transcription of the target gene, and preventing cell cycling. Such permanent modification may be anticipated to be more effective than oligonucleotide hybridization alone, while operating at a sub-toxic dose of mitomycin C. The site of the mitomycin- oligonucleotide conjugate bonding to RNA in vitro for promising drug candidates will be verified by melting point (Tm) measurements prior to drug activation and by the reverse transcriptase assay after drug activation.